class_docstr: A regular expression-based tokenizer at word boundary.
  This tokenizer default to support MegaMolBART.
  <https://catalog.ngc.nvidia.com/orgs/nvidia/teams/clara/models/megamolbart>
code: def ids_to_tokens(self, ids_list):
      if len(ids_list) and not isinstance(ids_list[0], list):
          ids_list = [ids_list]
          added_list = True
      else:
          added_list = False
  
      tokens_list = []
      for ids in ids_list:
          tokens = []
          for token_id in ids:
              token = self._decode_vocab.get(token_id)
              if token is None:
                  raise ValueError(
                      f"Token id {token_id} is not recognised"
                  )
              tokens.append(token)
  
          tokens_list.append(tokens)
  
      if added_list:
          return tokens_list[0]
      else:
          return tokens_list
  
imports: import os
  import re
  from typing import Optional
  import pandas
  from nemo.collections.common.tokenizers.char_tokenizer import TokenizerSpec
  from nemo.utils import logging
label_desc: Use image node_id 9 for calling the RegExTokenizer obj's underlying member method code with example usage: obj.ids_to_tokens(ids_list) and returns: tokens_list, tokens_list